An RNA mediated transformation of bacteria will be investigated to determine the consequences of introducing nucleic acid molecules composed of RNA and DNA into recipient cells. In previous studies such RNA-DNA hybrids were found capable of introducing donor drug resistence traits and producing both a stable transformant type and temporary transformants of Diplococcus pneumoniae (Pneumococcus). Persistence of introduced RNA or RNA-DNA Hybrid genetic determinants in transformant clones will be studied with the purpose of ascertaining their mode of action and probable non-chromosomal replication. The activity and chromosomal homology of the component RNA and DNA strands will be investigated in order to throw light on their structure, cellular origin and possible biological function.